HEART PHYSIOLOGY CONDUCTION SYSTEM Ana Ribi Mentor A

HEART PHYSIOLOGY & CONDUCTION SYSTEM Ana Ribić Mentor: A. Žmegač Horvat

PHYSIOLOGY

phase 1 - A-V Valves Open, Semilunar Valves Closed p wave of ECG atrial depolarization → atrial contraction → pressure increases → pressure gradient across the AV valves blood flow across the open atrioventricular (AV) valves "a-wave" ventricular end-diastolic volume (EDV) ventricular preload

phase 2 - All Valves Closed QRS complex → ventricular depolarization first heart sound (S 1) ventricular pressure rises - "isovolumetric" contraction

phase 3 - Aortic and Pulmonic Valves Open; AV Valves Remain Closed initial and rapid ejection of blood into the aorta and pulmonary arteries from the left and right ventricles total energy of blood ventricular maximal outflow pressure blood continues to flow into atria

phase 4 - Aortic and Pulmonic Valves Open; AV Valves Remain Closed after the QRS ventricular repolarization T-wave ventricular pressure falls slightly left atrial and right atrial pressures gradually rise

phase 5 - All Valves Closed aortic and pulmonic valves abruptly close second heart sound (S 2) isovolumetric relaxation dicrotic wave end-systolic volume LAP continues to rise http: //www. google. hr/imgres? imgurl=http: //www. stethographics. com/heart/im ages/s 123. jpg&imgrefurl=http: //www. stethographics. com/main/physiol ogy_hs_introduction. html&h=312&w=545&sz=55&tbnid=_Rg 21 HUd 1 Y 5 q. XM: &tbnh=76&tbnw=133&prev=/images%3 Fq%3 Dheart%2 Bsoun d&hl=hr&usg=__K 4 rsx 1 G_XCRY 8 TFd. It. VW 4 Fi 9 r. Bw=&ei=d. YSe. S 8 m_ A 4 ee_gb 0_qn 7 CQ&sa=X&oi=image_result&resnum=5&ct=image&ve d=0 CBk. Q 9 QEw. BA

phase 6 - A-V Valves Open intraventricular pressures fall below their respective atrial pressures ventricular filling third heart sound (S 3)

phase 7 - A-V Valves Open ventricles continue to fill with blood and expand → intraventricular pressures rise aortic pressure and pulmonary arterial pressures continue to fall

CONDUCTION SYSTEM 1. Sinoatrial node (SA node) sends the electrical impulse that triggers each heartbeat - upper area of the right atrium 2. Atrioventricular node (AV node) - sends an impulse through the nerve network to the ventricles 3. Common AV bundle 4. Right & left bundle branches nerve fibers that send impulses that cause the cardiac muscle tissue to contract

ELECTROCARDIOGRAM e-lek-tro-KAR-de-o-gram - EKG/ECG painless test that records the heart's electrical activity signal causes the heart to contract and pump blood and creates an electrical current that can be seen on a graph called an electrocardiogram signal causes the heartbeat each heartbeat has two basic parts: diastole and atrial and ventricular systole

P wave - represents the wave of depolarization that spreads from the SA node throughout the atria P-R interval represents the time between the onset of atrial depolarization and the onset of ventricular depolarization QRS complex ventricular depolarization ST segment - time at which the ventricle is depolarized and corresponds to the plateau phase of the ventricular action potential T wave - represents ventricular repolarization and is longer in duration than depolarization Q-T interval represents the time of both ventricular depolarization and

An EKG shows: how fast your heart is beating whether the rhythm of your heartbeat is steady or irregular the strength and timing of electrical signals as they pass through each part of your heart This test is used to detect and evaluate many heart problems, such as heart attack, arrhythmia and heart failure

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http: //www. cvphysiology. com/Heart Disease/HD 002. htm http: //www. nhlbi. nih. gov http: //www. wisegeek. com metacafe. com